From mboxrd@z Thu Jan 1 00:00:00 1970 From: Dario Faggioli Subject: Re: [PATCH v6 for Xen 4.7 1/4] xen: enable per-VCPU parameter settings for RTDS scheduler Date: Mon, 14 Mar 2016 11:05:30 +0100 Message-ID: <1457949930.3102.641.camel@citrix.com> References: <1457286958-5427-1-git-send-email-lichong659@gmail.com> <1457286958-5427-2-git-send-email-lichong659@gmail.com> <20160308190950.GT31271@citrix.com> <1457539804.3102.425.camel@citrix.com> <56E05F8F02000078000DAF15@prv-mh.provo.novell.com> <56E6866202000078000DBECD@prv-mh.provo.novell.com> <1457946623.3102.636.camel@citrix.com> <56E68F5202000078000DBF46@prv-mh.provo.novell.com> Mime-Version: 1.0 Content-Type: multipart/mixed; boundary="===============0803858749097639588==" Return-path: In-Reply-To: <56E68F5202000078000DBF46@prv-mh.provo.novell.com> List-Unsubscribe: , List-Post: List-Help: List-Subscribe: , Errors-To: xen-devel-bounces@lists.xen.org Sender: "Xen-devel" To: Jan Beulich , Chong Li Cc: Chong Li , Wei Liu , Sisu Xi , GeorgeDunlap , xen-devel , Meng Xu , Dagaen Golomb List-Id: xen-devel@lists.xenproject.org --===============0803858749097639588== Content-Type: multipart/signed; micalg=pgp-sha1; protocol="application/pgp-signature"; boundary="=-SSWumCJZ/2pcP7wd/36I" --=-SSWumCJZ/2pcP7wd/36I Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: quoted-printable On Mon, 2016-03-14 at 03:15 -0600, Jan Beulich wrote: > > > > On 14.03.16 at 10:10, wrote: > >=C2=A0 > > I think it has some value to have this in the logs. In fact, > > someone > > that ended up with small values --either by bug/chance, or in > > general > > without a specific need for them-- and is seeing > > performance/scheduling > > issues will still be able to find this. > >=20 > > And printing it somewhere else than in Xen is impractical (see my > > reply > > to Wei). > >=20 > > However, we may well print it just once, as soon as the first vcpu > > with > > potentially problematic parameters is hit, and then silence it. > >=20 > > Linux has things like WARN_ON_ONCE to do this: > > http://lxr.free-electrons.com/source/include/asm-generic/bug.h#L109 > > =C2=A0 > >=20 > > I don't see anything like it in Xen, so you'd need to either > > implement > > it, or arrange for something with the same effect locally. > One of the reasons we don't (yet) have this is because commonly > (like is the case here) printing such once globally isn't really what > you want - you'd much rather see it once per domain. > Ah, I did not know that was part of the reason, but it makes sense. However, for this specific case, I was also considering that, and I agree, if possible/not to difficult to implement, once per domain would indeed be better. Regards, Dario --=20 <> (Raistlin Majere) ----------------------------------------------------------------- Dario Faggioli, Ph.D, http://about.me/dario.faggioli Senior Software Engineer, Citrix Systems R&D Ltd., Cambridge (UK) --=-SSWumCJZ/2pcP7wd/36I Content-Type: application/pgp-signature; name="signature.asc" Content-Description: This is a digitally signed message part Content-Transfer-Encoding: 7bit -----BEGIN PGP SIGNATURE----- Version: GnuPG v2 iEYEABECAAYFAlbmjOoACgkQk4XaBE3IOsTxKgCgh4MuiJ+4vEHVxnSIHiMOQ8MX S7sAn1B8GkBZrtFB7NgtxjgvdcdJQFct =tBVm -----END PGP SIGNATURE----- --=-SSWumCJZ/2pcP7wd/36I-- --===============0803858749097639588== Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: base64 Content-Disposition: inline X19fX19fX19fX19fX19fX19fX19fX19fX19fX19fX19fX19fX19fX19fX19fX18KWGVuLWRldmVs IG1haWxpbmcgbGlzdApYZW4tZGV2ZWxAbGlzdHMueGVuLm9yZwpodHRwOi8vbGlzdHMueGVuLm9y Zy94ZW4tZGV2ZWwK --===============0803858749097639588==--